Publications by authors named "Ahmed O Alnajjar"

10 Publications

  • Page 1 of 1

Cr and Mn total, accessible species, and protein-fraction contents in plants used for traditional anti-diabetes treatment.

J Trace Elem Med Biol 2020 Dec 6;62:126645. Epub 2020 Sep 6.

Research Unit Analytical BioGeoChemistry, Helmholtz Center, Munich, German Research Center for Environmental Health, Neuherberg, Germany.

Background: Our survey has found eleven plants that have being consumed for traditional treatment of diabetes mellitus, particularly in Saudi Arabia and generally in many countries across the world. The literature reported about trace elements such as Cr and Mn positively affecting diabetes mellitus. The aim of this work is to determine the total, accessible element species, and protein-fraction contents of Cr and Mn in the edible parts of those plants.

Methods: The total contents of Mn were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES), while the total contents of Cr was determined by ICP-sector field (sf)-mass spectrometry (MS) due to lower concentration. The protein-fraction contents were determined in accessible element species by size-exclusion chromatography (SEC)-ICP-MS.

Results And Discussion: The separation was successfully carried out to quantify Cr and Mn bound up to 11 protein fractions. The examined plants recorded wide ranges of total contents (Cr 44.7-1880.0 μg/kg and Mn 3.7-59.0 mg/kg) and accessible element species contents (Cr 0.93-29.40 μg/kg and Mn 0.82-35.85 mg/kg). Also wide ranges of percentages of accessible element species contents to total contents of Cr (0.65-4.21%) and Mn (5.43-68.42%) were obtained. The hazardous indices of both trace elements Cr and Mn for all examined plants consumed by both children and adults were all < 1, indicating no probability of health risk to occur. Moreover, Cr as carcinogen element reported no probability of cancer risk to occur from the consumption of all examined plants. Irrespective of plant species, Cr was quantified in all SEC fractions (mainly protein fractions), with the exception of 1.9-3.7 kDa, while Mn was quantified in all SEC fractions with the exception of 100-120 and 1.3-3.7 kDa. Nevertheless, the majority of accessible Cr species contents bound to the 10-14 and 0.05-0.40 kDa fractions, while that of Mn bound to 0.05-0.40 kDa fraction. To gather, the benefits of specific plant species in terms of accessible Cr and Mn species contents, in addition to accessible Zn species contents reported in our previous study, Haloxylon Salicornicum, Olea Europaea Momordica and Charantia are recommended to be consumed for traditionally controlling T2DM.
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http://dx.doi.org/10.1016/j.jtemb.2020.126645DOI Listing
December 2020

Application of Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection (CE-CD): 2017-2020.

Crit Rev Anal Chem 2020 Aug 24:1-9. Epub 2020 Aug 24.

Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Cairo, Egypt.

Capacitively coupled contactless conductivity detection (CD) has emerged as influential to detect analytes that do not have chromogenic or fluorogenic functional group. Since our last review several new capillary electrophoresis (CE) methods coupled with (CE-CD) have been communicated. The aim of this review is to give an update of the almost all the new applications of CE-CD in the field of pharmaceutical, food and biomedical analysis covering the period from 2017 to April 2020. The utilization of CE with CD in the areas of pharmaceutical, food and biomedical analysis is presented. Finally, concluding remarks and outlooks are discussed.
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http://dx.doi.org/10.1080/10408347.2020.1809340DOI Listing
August 2020

A facile chemical synthesis of CuNiFeO nanoparticles as a nonprecious ferrite material for electrocatalytic oxidation of acetaldehyde.

Sci Rep 2020 Feb 17;10(1):2761. Epub 2020 Feb 17.

Department of Chemistry, Faculty of Science, Sohag university, Sohag, 82524, Egypt.

In the present work, Cu-doped nickel ferrite (CuNiFeO) nanoparticles (CuNFNPs) were chemically fabricated by adding citric acid as a capping agent followed by combustion and calcination for acetaldehyde oxidation reaction (AOR) in KOH electrolytes. The as-prepared CuNFNPs were studied in terms of Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), Field emission scanning electron microscope (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) specific surface area analyses. The morphology of CuNFNPs has sponges-structure containing irregular pores. Additionally, XRD analysis indicated that the prepared CuNFNPs have a cubic-crystals ferrite without the existence of impurities and the crystal size around 20.2 nm. The electrooxidation of acetaldehyde by the presented CuNFNPs was investigated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) in OH media. Furthermore, the effects of OH and acetaldehyde on the electrocatalytic performance were studied with and without Cu-doping in addition to EIS and CA studies which confirm the high-performance of CuNFNPs as an electrocatalyst for AOR.
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http://dx.doi.org/10.1038/s41598-020-59655-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026399PMC
February 2020

Investigation of total zinc contents and zinc-protein profile in medicinal plants traditionally used for diabetes treatment.

Biometals 2020 02 6;33(1):65-74. Epub 2019 Dec 6.

Research Unit Analytical BioGeoChemistry, Helmholtz Center, Munich, Germany.

This study aims at the assessment of total zinc contents, water zinc extract contents and zinc-protein profile in medicinal plants traditionally used for diabetes treatment. While zinc-protein profile was screened in plant samples using the online coupling of size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS), total zinc contents and zinc water extract contents were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). The analysis of two certified reference materials with similar matrix for total zinc content revealed recovery values of 97.1% and 100.5% while the average of recovery of the summed Zn concentrations from protein fractions compared to total Zn was 103.0 ± 4.8%. Based on the FAO/WHO classification, Sesamum indicum, Nigella sativa, Trigonella Foenum-graecum and Pennisetum glaucum are classified as highest Zn-content. For protein profile, zinc was quantified in 330-430 and 50-60 kDa fractions of all examined plants while no contents were quantified in the inorganic fraction 0.05-0.4 kDa of all plant species. Also, only three plant species recorded Zn contents in the phytate fraction (0.9-1.5 kDa fraction). The fruits of the Momordica Charantia and the Citrullus colocynthis were with the highest extractable zinc concentration; 13.55 ± 0.45 and 10.08 ± 0.63 mg/kg, respectively. The highest Zinc capturing capacity was reported for the 50-60 and 70-87 KDa protein fractions.
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http://dx.doi.org/10.1007/s10534-019-00230-3DOI Listing
February 2020

Development of a CZE method for the quantification of pseudoephedrine and cetirizine.

J Chromatogr Sci 2014 Oct 20;52(9):1104-8. Epub 2013 Sep 20.

Department of Chemistry, College of Science, King Khalid University, PO Box 9004, Abha 61321, Saudi Arabia

Pseudoephedrine and cetirizine have been combined in dosage forms with more therapeutic benefits when compared with single-drug treatment. The current manuscript reports the development of the first capillary zone electrophoresis (CZE) assay method for that combination. The effects of pH and buffer concentration on resolution, noise, migration time and peak area were examined employing experimental design approach. The analytes were electropherographed into a 50.2 cm-long and 50 µm i.d. fused-silica capillary column using 10 mmol/L borate at pH 8.3 with a potential of 25 kV at 25°C and UV detection at 214 nm. The method was successfully validated in order to verify its suitability for pharmaceutical analysis for the purposes of quality control. Over previous high-performance liquid chromatographic methods, the current CZE method features the benefits of the use of cost-effective electrolyte, besides high sample throughput (11 samples/h). Furthermore, other analytical results including linear dynamic ranges, recovery (96.9-98.1%), intra- and interday precision (relative standard deviation ≤ 1.70%) as well as the limits of detection and quantification (≤2.65 µg/mL) were all satisfactory for the intended purpose.
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http://dx.doi.org/10.1093/chromsci/bmt141DOI Listing
October 2014

Native fluorescent detection with sequential injection chromatography for doping control analysis.

Chem Cent J 2013 Aug 28;7(1):144. Epub 2013 Aug 28.

Department of Chemistry, College of Science, King Khalid University, P,O, Box 9004, Abha, Saudi Arabia.

Background: Sequential injection chromatography (SIC) is a young, ten years old, separation technique. It was proposed with the benefits of reagent-saving, rapid analysis, system miniaturization and simplicity. SIC with UV detection has proven to be efficient mostly for pharmaceutical analysis. In the current study, a stand-alone multi-wavelength fluorescence (FL) detector was coupled to an SIC system. The hyphenation was exploited for developing an SIC-FL method for the separation and quantification of amiloride (AML) and furosemide (FSM) in human urine and tablet formulation.

Results: AML and FSM were detected using excitation maxima at 380 and 270 nm, respectively, and emission maxima at 413 and 470 nm, respectively. The separation was accomplished in less than 2.0 min into a C18 monolithic column (50 × 4.6 nm) with a mobile phase containing 25 mmol/L phosphate buffer (pH 4.0): acetonitrile: (35:65, v/v). The detection limits were found to be 12 and 470 ng/mL for AML and FSM, respectively.

Conclusions: The proposed SIC-FL method features satisfactory sensitivity for AML and FSM in urine samples for the minimum required performance limits recommended by the World Anti-Doping Agency, besides a downscaled consumption of reagents and high rapidity for industrial-scale analysis of pharmaceutical preparations.
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http://dx.doi.org/10.1186/1752-153X-7-144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3851596PMC
August 2013

A conventional HPLC-MS method for the simultaneous determination of ofloxacin and cefixime in plasma: Development and validation.

J Basic Clin Pharm 2013 Mar;4(2):36-41

Department of Chemistry, College of Science, King Faisal University, P. O. Box 400, Al-Ahsa 31982, Saudi Arabia.

Objective: A simple, rapid, and sensitive high performance liquid chromatography-mass spectrometry (HPLC-MS) method was developed and validated for the simultaneous determination of ofloxacin (OFL) and cefixime (CEF) in human plasma using the moxifloxacin as internal standard.

Methodology: Analytes were separated using an Agilent LCMS system equipped with a Zorbax eclipse XBD C18 column (150 mm × 4.6 mm i.d., 5 μm) and using a mobile phase consisting of a mixture of acetonitrile, methanol and 0.5% formic acid in a ratio of 23:10:67% v/v and flow rate was set at 0.6 mL/min. Plasma samples were extracted using the protein precipitation with acetonitrile and analyzed by positive ion mode.

Results: The linearity of the proposed method was investigated in the concentration range of 4-500 ng/mL (r = 0.9996) for OFL and 40-6000 ng/mL (r = 0.9998) for CEF. The lower limits of quantification were 4 ng/mL and 40 ng/mL for OFL and CEF respectively, which reach the level of both drugs possibly found in human plasma. Further, the reported method was validated as per the ICH guidelines and found to be well within the acceptable range.

Conclusion: The proposed method is simple, rapid, accurate, precise, and appropriate for pharmacokinetic and therapeutic drug monitoring in the clinical laboratories.
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http://dx.doi.org/10.4103/0976-0105.113606DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3979261PMC
March 2013

Capillary electrophoresis assay method for metoprolol and hydrochlorothiazide in their combined dosage form with multivariate optimization.

J Chromatogr Sci 2013 Jan 28;51(1):92-7. Epub 2012 Jun 28.

Department of Chemistry, College of Science, King Faisal University, Hofuf, Saudi Arabia.

The current manuscript reports the first capillary electrophoresis method for the separation and quantification of metoprolol (MET) and hydrochlorothiazide (HCT) in their combined dosage form. MET and HCT were detected at 240 and 214 nm, respectively, using a photodiode array detector. The univariate approach was used for optimizing voltage, injection time and capillary temperature. The factorial design with response surface plots, as a multivariate approach, was used to study the effect of buffer concentration and pH on resolution, peak area and migration time. The optimum conditions were 50 mmol/L phosphate at pH 9.5, injection time 10.0 s, voltage 25 kV and capillary temperature 25°C. The method was linear in the range of 2.5-250 µg/mL for both drugs with correlation coefficients above 0.9997. Additionally, acceptable recovery of the contents of MET and HCT in their formulations (96.0-100.3%) with acceptable precision (1.38-2.60 %) were achieved. Moreover, the limits of detection of MET and HCT were 0.02 and 0.01 µg/mL, respectively, which were suitable for pharmaceutical analysis.
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http://dx.doi.org/10.1093/chromsci/bms107DOI Listing
January 2013

Validation of a capillary electrophoresis method for the simultaneous determination of amlodipine besylate and valsartan in pharmaceuticals and human plasma.

Authors:
Ahmed O Alnajjar

J AOAC Int 2011 Mar-Apr;94(2):498-502

King Faisal University, College of Science, Department of Chemistry, PO Box 400, Al-Ahssa 31982, Saudi Arabia.

A rapid, simple, and sensitive capillary electrophoresis (CE) method was developed and validated for the simultaneous determination of amlodipine (AML) and valsartan (VAL) in pharmaceuticals and human plasma using a UV photodiode array detector. Electrophoretic conditions were optimized to improve separation, sensitivity, and rapidity. The optimal conditions were 25 mM phosphate buffer at pH 8.0, injection time 10.0 s, voltage 25 kV, and column temperature 25 degrees C, with detection at 214 nm. The method was found to be linear in the range of 1.0-35 and 1.0-350 mg/L, with weighted regression 0.9999 and 0.9994, for AML and VAL, respectively. Validation of the method showed acceptable intraday and interday accuracy (85.5-95.3%) and precision (RSD 1.64-4.2%) in pharmaceutical formulation and human plasma analysis. The sensitivity of the method was enhanced by both optimization of the CE procedure and preconcentration performed by liquid-liquid extraction. The LOD for both AML and VAL was 0.03 mg/L, which allows analysis at the level of the drugs possibly found in human plasma. Therefore, the proposed method is suitable for QC in pharmaceutical laboratories and therapeutic drug monitoring in clinical laboratories.
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June 2011

Synthesis and characterization of novel azo-morphine derivatives for possible use in abused drugs analysis.

Eur J Med Chem 2008 Feb 14;43(2):357-63. Epub 2007 Apr 14.

Department of Chemistry, College of Science, King Faisal University, P.O. Box 380, 31982 Hofuf, Saudi Arabia.

A new simple and fast spectroscopic method was presented as a new marker for heroin use. Novel azo-morphine derivatives with spectroscopic absorption peaks ranging from 330-470 nm, were synthesized by the coupling of morphine (M) and 6-acetyl morphine (6-AM) with freshly prepared diazonium salt of aniline hydrochloride at 0 degrees C. However, no reaction was observed with codeine under the same reaction conditions. Separation of azo dyes was performed by TLC using tetrahydrofuran and dichloromethane in the ratio 1:1. The chemical structure of the products was established by their microanalysis, NMR, IR, UV-vis, and mass spectroscopies. Electronic absorption and excitation spectra of the dyes were measured in solvents of different polarities. The dyes exhibited positive solvatochromism, i.e., a bathochromic band shift as the solvent polarity is increased. Also, the fluorescence quantum yield was sensitive to the polarity and the pH of the medium. The UV-vis spectroscopy of spiked compounds in human urine samples was also reported. The drugs (M, 6-AM and mixture of both) were coupled with freshly prepared diazonium salt even at very low concentration of the drugs 10(-9)M.
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http://dx.doi.org/10.1016/j.ejmech.2007.03.034DOI Listing
February 2008